1. Field of the Invention PA1 Reference 1: "Map Information Expert System GENTLE", by Shimada and Ejiri, a preparatory draft for the Advanced Database System Symposium in FY 1985, pp 93-101, Information Processing Society of Japan; PA1 Reference 2: "Introduction to Three-Dimensional Graphics based on C Language" by Shigeo Ishii, Gijutsu Hyoronsha, 1985; PA1 Reference 3: "Principles of Database Systems", by Ullman, J. D., Computer Science Press, Potomac, Md., 1980; PA1 Reference 4: "Object-oriented Programming: An Evolutionary Approach", by Brad J. Cox, Addison-Wesley Cop. Inc., 1988; PA1 Reference 5: "Description by Viewpoint and Automatic Processing Propagating Mechanism in Mapping System Manipulating Multimedia", by Shimade, et. al., Proc. Advanced Database System Symposium, 1989; PA1 Reference 6: "Division and Recognition of Superposed Drawings in Multimedia type Power Drawing Information System", by Chikada, Shimada, Miyatake and Matsushima, the national meeting of The Institute of Electronics Information and Communication Engineers of Japan, FY 1988, SD-7-4; and PA1 Reference 7: "Application of Map Information--for forming regional appearance" by Goji Sasada, Graphic Processing Information Center, 1983.
The present invention relates to a method of using objects for three-dimensionally displaying figure information and a system therefor. Particularly, the present invention relates to a method for making an effective three-dimensional display of buildings and a system therefor, in addition to a conventional two-dimensional display of a map, for tasks requiring map information such as for facility inspections and urban designing public enterprises and architectural and civil engineering enterprises.
2. Description of Related Art
The following references have been known relating to the present invention. These references are suitably cited in the following explanation of the present invention.
As a relevant patent application, a U.S. patent application (No. 07/630,328) titled "Method of Processing Multimedia Data in Multimedia Database and System Therefor" was filed on Nov. 29, 1990. One of the inventors of this relevant application (Mr. Shimada) is also one of the inventors of the present application. The relevant application is incorporated in the present application as a reference.
In recent years, multistory buildings and underground markets have been developed in the metropolitan centers.
In order to identify buildings and houses or to comprehend the layout of shops and stores, three-dimensional display information such as numbers of floors of buildings and numbers of floors of underground markets has been become more important in addition to conventional two-dimensional information such as maps. Under such a situation, in each of public enterprises and architectural and civil engineering enterprises, three-dimensional map displays which take account of heights of buildings as well as figures of the buildings above the ground surface level have come to be required because using only conventional two-dimensional map displays is not sufficient for performing works such as facility inspections and urban designing for which maps are used.
In order to meet these requirements, various kinds of three-dimensional bird's-eye displays using design data have already been carried out in the field of an architectural CAD, as shown in the reference 7. In the architectural CAD, data of buildings and the like are converted into in complete three-dimensional data and stored in a data base. By using these data the buildings and highways can be displayed in a three-dimensional manner when they are viewed from any desired direction.
Therefore, a method would be considered wherein various attribute data of the buildings having three-dimensional characteristics are displayed in one-to-one corresponding relation with the buildings, after the three-dimensional bird's-eye display is made.
Further, a method of applying shading to the display considering a light source has been progressed recently, in addition to a mere three-dimensional display using a wire frame, so that a more realistic display has gradually been made possible.
However, in application of the method shown in the above reference 7 to a map information system as an example of a figure information system, it is necessary to obtain figure data of building as data of complete three-dimensional coordinate system (x, y, z) as in the architectural and civil engineering CAD. Therefore, the following three problems exist.
As the first problem, in the case of a map information system, there is a heavy load when displaying various kinds of attribute information in correspondence with figure elements on a two-dimensional display of map data which include a large amount of figure elements such as roads and house frames. Therefore it is not practical for a complete three-dimensional display of the map data as in the architectural CAD system. In other words, it is assumed that the map data is merely stored in a data base which map data includes coordinate data indicative of figures of roads and buildings, and symbols for churches, banks, and the like, and texts for display. Therefore, in the case of retrieving attribute data by using a displayed building or text as a key for the retrieval, a z-coordinate in the height direction needs to be searched for route search processing and search processing within a near range in addition to two-dimensional coordinates (x, y). Therefore, a time for executing various retrieval processings is expected to become extremely long.
As the second problem, in a map information system, in order to obtain complete detailed values of three-dimensional coordinates for buildings as defined in the architectural CAD system, it is necessary to obtain such detailed data by searching each building, resulting in an enormous amount of search processes. Therefore, it is almost impossible to completely build a three-dimensional data base for this purpose.
As the third problem, in the case of displaying various kinds of attribute data on the above three-dimensional display, it is expected to be extremely difficult to confirm at a later stage corresponding relation relationship between buildings and attributes.